Indicate by check mark whether the
registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and
(2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be
submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such
files). Yes x No ¨

Indicate by check mark
whether registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company See the definitions of large accelerated filer, accelerated filer and smaller reporting
company in Rule 12b-2 of the Exchange Act.

Large accelerated filer ¨

Accelerated filer ¨

Non-accelerated filer x (Do not check if a smaller reporting company)

Smaller reporting company ¨

Indicate by check mark whether registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).
Yes ¨ No x

As of April 14, 2009, the
registrant had 18,953,937 shares of Common Stock ($0.0001 par value) outstanding.

Indicate by check mark whether the registrant:
(1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and
(2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company See the definitions
of large accelerated filer, accelerated filer and smaller reporting company in Rule 12b-2 of the Exchange Act.

Large accelerated filer ¨

Accelerated filer x

Non-accelerated filer ¨

Smaller reporting company ¨

(Do not check if a smaller reporting company)

Indicate by check mark whether registrant is a shell company (as defined in Rule 12b-2 of the Exchange
Act). ¨ Yes x No

As of October 15, 2008, the registrant had 18,943,937 shares of Common Stock ($0.0001 par value) outstanding.

Indicate by check mark whether the registrant:
(1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and
(2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company See the definitions
of large accelerated filer, accelerated filer and smaller reporting company in Rule 12b-2 of the Exchange Act.

Large accelerated filer ¨

Accelerated filer x

Non-accelerated filer ¨ (Do not check if a smaller reporting company)

Smaller reporting company ¨

Indicate by check mark whether registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

¨ Yes x No

As of July 17, 2008, the registrant had 18,933,588 shares of Common Stock ($0.0001 par value) outstanding.

Indicate by check mark whether the registrant:
(1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and
(2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer (as defined in Rule 12b-2 of the Exchange Act.)

Large accelerated filer ¨ Accelerated filer x Non-accelerated filer ¨

Indicate by check mark whether registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). ¨ Yes x No

As of April 11, 2008, the
registrant had 18,930,673 shares of Common Stock ($0.0001 par value) outstanding.

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934
during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer (as defined in Rule 12b-2 of the Exchange Act.)

Large accelerated filer ¨ Accelerated filer x Non-accelerated filer ¨

Indicate by check mark whether registrant is a shell company (as defined in Rule 12b-2 of the Exchange
Act). ¨ Yes x No

As of October 9, 2007, the registrant had 18,861,398 shares of Common Stock ($0.0001 par value) outstanding.

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934
during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer (as defined in Rule 12b-2 of the Exchange Act.)

Large accelerated filer ¨ Accelerated filer x Non-accelerated filer ¨

Indicate by check mark whether registrant is a shell company (as defined in Rule 12b-2 of the Exchange
Act). ¨ Yes x No

As of July 26, 2007, the registrant had 18,827,534 shares of Common Stock ($0.0001 par value) outstanding.

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934
during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer (as defined in Rule 12b-2 of the Exchange Act.)

Large accelerated filer ¨ Accelerated filer x Non-accelerated filer ¨

Indicate by check mark whether registrant is a shell company (as defined in Rule 12b-2 of the Exchange
Act). ¨ Yes x No

As of April 23, 2007, the registrant had 18,817,951 shares of Common Stock ($0.0001 par value) outstanding.

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934
during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer (as defined in Rule 12b-2 of the Exchange Act.)

Large accelerated filer ¨ Accelerated filer x Non-accelerated filer ¨

Indicate by check mark whether registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

¨ Yes x No

As of October 24, 2006, the registrant had 18,785,864 shares of Common
Stock ($0.0001 par value) outstanding.

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934
during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether NAI is a large accelerated filer, an accelerated filer, or a non-accelerated filer (as defined in Rule 12b-2 of the Exchange Act.)

Large accelerated filer ¨ Accelerated filer x Non-accelerated filer ¨

Indicate by check mark whether NAI is a shell company (as defined in Rule 12b-2 of the
Exchange Act).

¨ Yes x No

As of July 31,
2006, the registrant had 18,779,880 shares of Common Stock ($0.0001 par value) outstanding.

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934
during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether NAI is a large accelerated filer, an accelerated filer, or a non-accelerated filer (as defined in Rule 12b-2 of the Exchange Act.)

Large accelerated filer ¨ Accelerated filer x Non-accelerated filer ¨

Indicate by check mark whether NAI is a shell company (as defined in Rule 12b-2 of the Exchange Act).

¨ Yes x No

As of April 25, 2006, the registrant had 18,741,662 shares of Common Stock ($0.0001 par value)
outstanding.